The art is replete with various types and sizes of pneumatic and other powered, positive displacement fluid-dispensing apparatus for a wide variety of industrial, specialized, and home applications, including, for example, viscous fluid cartridge dispensers of the type disclosed in the earlier U.S. Pat. No. 5,816,455 of the present inventor herein and of common assignee.
Where hand-held application guns are desirable, moreover, it is tedious and tiring to operate successive manually or pneumatic-triggered "shots" in jolts.
It has also been proposed to provide microprocessor- controlled and smoother electrically driven pumps, as described, for example, on p. 1025-6 of the Cole-Parmer Instrument Company instruments catalog of 1993-1994, for single or multiple-component fluid dispensing; and, where hand-held operation is desired, for providing electric motor driven rods for expelling fluids from cartridges or syringes, with a hand-held apparatus, as, for example, in U.S. Pat. Nos. 5,630,527 and 5,765,722.
In dispensers of the prior art using electric motor drives, however, the motor has generally been mounted in-line with the drive rod(s) or screw, that actuates plungers to dispense fluid from cartridges or syringes or the like, with the rod or screw often passing axially through the motor structure itself, as for example, in the last-named references. For hand-held operation with such electric motor-drive rod in-line structures, the hand holds the apparatus longitudinally like a pencil or soldering iron. There are important applications, however, as in use by a dentist within a patient's mouth, and in other applications, as well, where such in-line holding of the apparatus blocks the view required to apply and control the dispensed fluid by the operator, such as the dentist. Similarly, where the operator must have an unobstructed view of the dispensing within an enclosure or the like, such hand-held operation again blocks satisfactory viewing.
It is to the solution of these and other problems more particularly with hand-held fluid dispensing guns and the like, accordingly that the present invention is primarily directed.
The invention is also an improvement over pneumatic systems that require an air line. Because the invention provides for cordless operation via a battery pack, the system is portable and therefore useful in environments where running an air line or power cord is prohibitive.